Top 50 infrastructure as code interview questions and answers for devops engineer

Top 50 Infrastructure as Code (IaC) Interview Questions and Answers for DevOps Engineers

Welcome to this comprehensive study guide, dated 28 November 2025, designed to prepare aspiring and experienced DevOps Engineers for interview questions focusing on Infrastructure as Code (IaC). This guide distills the core concepts, popular tools, best practices, and practical scenarios you'll encounter, helping you confidently tackle even the most challenging IaC questions. Master IaC to streamline your infrastructure management and excel in your DevOps career.

Table of Contents

1. Understanding Infrastructure as Code (IaC)
2. Key Benefits and Principles of IaC
3. Popular IaC Tools for DevOps
4. Implementing IaC in the DevOps Pipeline
5. IaC Best Practices and Security Considerations
6. Common IaC Challenges and Solutions
7. Preparing for IaC Interview Questions
8. Frequently Asked Questions (FAQ)
9. Further Reading

Understanding Infrastructure as Code (IaC)

Infrastructure as Code (IaC) is a fundamental practice in modern DevOps methodologies, where infrastructure provisioning and management are treated like software development. Instead of manual configuration, infrastructure resources such as virtual machines, networks, and databases are defined in machine-readable definition files. These files are then version-controlled, allowing for consistent, repeatable, and automated deployments.

Using code to manage infrastructure allows teams to apply practices from software development, like version control, testing, and continuous integration/continuous deployment (CI/CD). This approach significantly reduces human error and accelerates deployment cycles. IaC ensures that your development, staging, and production environments are identical, preventing "configuration drift" issues.

Example: Declarative vs. Imperative IaC

IaC tools generally fall into two categories:

• Declarative IaC: You define the desired end state of your infrastructure, and the tool figures out how to get there. Examples include Terraform and AWS CloudFormation.

  
  resource "aws_instance" "web" {
    ami           = "ami-0abcdef1234567890"
    instance_type = "t2.micro"
    tags = {
      Name = "HelloWorldWeb"
    }
  }
  

• Imperative IaC: You write scripts that specify the exact steps to achieve the desired state. Examples include Ansible and Chef.

  
  ---
  - name: Install Nginx
    hosts: webservers
    tasks:
      - name: Ensure nginx is installed
        apt:
          name: nginx
          state: present
      - name: Ensure nginx is running
        service:
          name: nginx
          state: started
  

Key Benefits and Principles of IaC

Embracing Infrastructure as Code brings numerous advantages for DevOps teams. Understanding these benefits is crucial for any aspiring DevOps Engineer preparing for IaC interview questions.

• Consistency and Reliability: IaC eliminates manual errors, ensuring that every deployment is identical and reproducible across all environments. This consistency minimizes environment-specific bugs.
• Speed and Efficiency: Automating infrastructure provisioning drastically reduces deployment times. Resources can be spun up or scaled down rapidly in response to demand.
• Version Control: Infrastructure definitions are stored in version control systems (e.g., Git). This provides a complete history of changes, enables rollbacks, and facilitates collaboration.
• Cost Savings: By automating resource provisioning and de-provisioning, IaC helps optimize cloud spending. You only pay for what you use, when you use it.
• Improved Collaboration: Teams can work together on infrastructure definitions, review changes, and merge them using standard software development workflows.
• Security: IaC allows for the definition of security policies and configurations directly in code, ensuring they are consistently applied and auditable.

Practical Action Item: Implement a Simple IaC Project

Start with a small project like deploying a single virtual machine or a simple web server using a tool like Terraform or Ansible. Focus on versioning your configuration files from day one to grasp IaC fundamentals.

Popular IaC Tools for DevOps

The landscape of IaC tools is diverse, each with its strengths and use cases. DevOps Engineers often work with several of these, so familiarity is key for interviews covering IaC.

• Terraform (HashiCorp): A declarative, cloud-agnostic tool for provisioning and managing infrastructure across various cloud providers (AWS, Azure, GCP) and on-premises solutions. It excels at managing the entire lifecycle of infrastructure.
• Ansible (Red Hat): An open-source imperative automation engine primarily used for configuration management, application deployment, and orchestration. It's agentless, using SSH to connect to target machines.
• AWS CloudFormation: Amazon's native declarative IaC service for provisioning and managing AWS resources. It integrates deeply with AWS services.
• Azure Resource Manager (ARM Templates): Microsoft Azure's native declarative IaC service for provisioning resources within the Azure ecosystem.
• Google Cloud Deployment Manager: Google Cloud's native declarative IaC service for defining and deploying resources.
• Puppet & Chef: Older, agent-based imperative configuration management tools, still widely used in enterprise environments, primarily for managing server configurations.

Code Snippet: Terraform for AWS S3 Bucket

This snippet demonstrates how to define an AWS S3 bucket using Terraform's HashiCorp Configuration Language (HCL).

resource "aws_s3_bucket" "my_bucket" {
  bucket = "my-unique-iac-bucket-2025" # Must be globally unique
  acl    = "private"

  tags = {
    Environment = "Dev"
    Project     = "IaCGuide"
  }
}

Implementing IaC in the DevOps Pipeline

IaC is a cornerstone of a robust DevOps pipeline, enabling continuous integration and continuous deployment (CI/CD) for infrastructure. Integrating IaC effectively streamlines development and operations, a common topic in DevOps engineer interviews.

• Version Control Integration: IaC scripts are stored in Git repositories, triggering CI pipelines on code commits. This ensures all infrastructure changes are tracked and auditable.
• Automated Testing: CI pipelines can include automated tests for IaC code (e.g., syntax validation, linting, policy checks like OPA). Tools like Terratest or Kitchen-CI help validate infrastructure deployments before they reach production.
• Continuous Delivery/Deployment: Upon successful testing, IaC tools deploy infrastructure changes automatically to various environments (dev, staging, production). This enables rapid and reliable releases.
• Drift Detection: Tools can monitor deployed infrastructure and compare it to the IaC definitions, alerting if discrepancies ("drift") occur. This helps maintain environment consistency.

Practical Action Item: Automate IaC Deployment

Set up a simple CI/CD pipeline (e.g., using GitLab CI/CD, GitHub Actions, Jenkins) to automatically `terraform plan` and `terraform apply` a basic infrastructure change upon merging code to a main branch.

IaC Best Practices and Security Considerations

To maximize the benefits of IaC and minimize risks, adhering to best practices is essential for any DevOps Engineer. Security should always be a top priority when dealing with Infrastructure as Code.

• Modularity and Reusability: Break down infrastructure into smaller, reusable modules or components. This promotes consistency, reduces duplication, and simplifies management.
• Idempotence: Ensure your IaC scripts can be run multiple times without causing unintended side effects. Each run should result in the same infrastructure state, guaranteeing predictability.
• State Management: Understand how your IaC tool manages state (e.g., Terraform state files). Securely store and manage state, especially in collaborative environments, to prevent conflicts.
• Security First: Embed security practices directly into your IaC. Use least privilege principles for service accounts, encrypt sensitive data (e.g., using AWS KMS or Azure Key Vault), and implement network segmentation.
• Peer Reviews: Just like application code, IaC changes should undergo peer review to catch errors, enforce standards, and share knowledge across the team.
• Documentation: Keep your IaC code well-documented, explaining its purpose, dependencies, and how to use it. Clear documentation aids maintainability and onboarding.

Code Snippet: Using Variables for Modularity (Terraform)

# main.tf
resource "aws_s3_bucket" "my_app_bucket" {
  bucket = var.bucket_name
  acl    = var.bucket_acl
  tags   = var.common_tags
}

# variables.tf
variable "bucket_name" {
  description = "Name for the S3 bucket (must be unique)."
  type        = string
}

variable "bucket_acl" {
  description = "Access Control List for the S3 bucket."
  type        = string
  default     = "private"
}

variable "common_tags" {
  description = "Common tags for resources."
  type        = map(string)
  default = {
    ManagedBy = "Terraform"
  }
}

Common IaC Challenges and Solutions

While powerful, IaC comes with its own set of challenges that DevOps Engineers must be prepared to address. Interview questions often probe how you handle these complexities.

• State File Management: Managing and securing state files (especially for Terraform) in collaborative environments can be complex. Solution: Use remote backends (e.g., S3, Azure Blob Storage) with locking and encryption.
• Configuration Drift: Manual changes outside of IaC can lead to discrepancies between code and actual infrastructure. Solution: Implement drift detection tools and enforce IaC-only changes through policy.
• Learning Curve: New tools and paradigms require time for teams to adopt. Solution: Provide comprehensive training, clear documentation, and start with small, manageable IaC projects to build confidence.
• Tool Sprawl: Choosing and integrating multiple IaC tools can be overwhelming. Solution: Standardize on a few core tools that best fit your organization's needs and integrate them effectively.
• Security Vulnerabilities: Misconfigured IaC can expose infrastructure to security risks. Solution: Integrate security scanning tools (e.g., Checkov, tfsec) into CI/CD pipelines and conduct regular audits.

Preparing for IaC Interview Questions

Acing IaC-focused interview questions requires a blend of conceptual understanding and practical experience. Here's how to prepare effectively for your DevOps engineer role:

• Master the Fundamentals: Clearly define IaC, its benefits, and its core principles. Understand the declarative vs. imperative approaches and their suitable use cases.
• Know Key Tools: Be proficient in at least one major IaC tool (Terraform is highly recommended) and have a working knowledge of others. Discuss their pros and cons, and when to choose one over another.
• Understand DevOps Integration: Explain how IaC fits into CI/CD, version control, and overall DevOps workflows. Articulate the benefits of this integration.
• Discuss Best Practices: Be ready to talk about modularity, idempotence, state management, and security considerations. Provide examples of how you've applied these.
• Problem-Solving Scenarios: Prepare to discuss how you would troubleshoot IaC issues, handle configuration drift, or manage sensitive data within an IaC context.
• Hands-on Experience: Demonstrate practical skills. Be ready to walk through your code or explain past projects where you successfully implemented IaC solutions. Practical examples always impress.

Frequently Asked Questions (FAQ)

Here are answers to common questions regarding Infrastructure as Code for DevOps roles, providing concise explanations for typical interview scenarios.

• Q: What is the primary difference between IaC and traditional infrastructure management?
  A: IaC treats infrastructure like software, using code and automation, while traditional management relies on manual configuration and processes, leading to inconsistencies and errors.
• Q: Why is Terraform so popular for IaC?
  A: Terraform is popular due to its cloud-agnostic nature, allowing a single workflow to manage resources across multiple providers, and its powerful declarative configuration language.
• Q: What is "configuration drift" in IaC, and how do you prevent it?
  A: Configuration drift occurs when actual infrastructure deviates from its IaC definition. It's prevented by enforcing IaC-only changes, using automated drift detection, and regular reconciliations.
• Q: Can IaC improve security? How?
  A: Yes, IaC improves security by allowing security policies and configurations to be defined, version-controlled, and consistently applied in code, reducing human error and enabling automated audits.
• Q: What's the role of Git in an IaC workflow?
  A: Git is crucial for version controlling IaC code, tracking changes, facilitating collaboration among team members, enabling code reviews, and providing a rollback mechanism for infrastructure changes.

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Further Reading

To deepen your understanding of Infrastructure as Code and prepare further for your DevOps journey, consider exploring these authoritative resources:

• Terraform Documentation: The official source for learning HashiCorp Terraform, offering comprehensive guides and tutorials.
• Ansible Documentation: Comprehensive guides and examples for using Red Hat Ansible for configuration management and automation.
• AWS CloudFormation Resources: Official tutorials and documentation from Amazon Web Services for managing AWS infrastructure as code.

This guide has equipped you with a solid foundation in Infrastructure as Code, covering essential concepts, popular tools, best practices, and preparation strategies for common interview questions. By mastering IaC, you position yourself as a valuable asset in any DevOps team, capable of building and managing robust, scalable, and automated infrastructure. Continue practicing and exploring the tools to solidify your expertise and confidently excel in your career.

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1. What is Infrastructure as Code (IaC)?

Infrastructure as Code is a DevOps practice where servers, networks, and cloud resources are provisioned using machine-readable configuration files instead of manual processes. IaC ensures consistency, automation, repeatability, and faster environment deployment.

2. What are the benefits of IaC?

IaC provides automation, faster provisioning, environment consistency, version control, reduced human errors, and scalability. It enables teams to define infrastructure declaratively or imperatively and reproduce environments across dev, test, and production easily.

3. What are the declarative and imperative IaC approaches?

Declarative IaC describes the desired state of infrastructure, while imperative IaC defines step-by-step commands to reach that state. Declarative tools ensure idempotency, whereas imperative methods require explicit operational control and ordered execution.

4. What is Terraform?

Terraform is an open-source IaC tool by HashiCorp that provisions cloud resources across multiple providers. It uses HCL syntax, supports declarative configuration, enables reusable modules, and maintains state files to track infrastructure deployment changes.

5. What is a Terraform state file?

The Terraform state file stores the current state of deployed infrastructure. It helps Terraform detect changes, plan updates, and maintain mapping between resources and configurations. Remote state storage ensures security, locking, and team collaboration.

6. What is AWS CloudFormation?

AWS CloudFormation is Amazon’s IaC service that provisions cloud resources using YAML or JSON templates. It automates AWS infrastructure creation through stacks, supports drift detection, rollback, change sets, and integrates with CI/CD for environment management.

7. What is Ansible?

Ansible is an agentless IaC and configuration management tool using YAML playbooks. It automates provisioning, configuration, and application deployment through SSH or WinRM, providing idempotent execution and simple, human-readable automation workflows.

8. What is Pulumi?

Pulumi is an IaC tool that allows developers to write infrastructure code using languages like TypeScript, Python, Go, and C#. It combines IaC with programming logic, enabling reusable modules, cross-cloud deployments, and modern cloud-native automation.

9. What is idempotency in IaC?

Idempotency means executing the same IaC script multiple times results in the same infrastructure state. Tools like Ansible, Terraform, and CloudFormation use idempotent logic to ensure reliability, consistency, and predictable deployment outcomes.

10. What are Terraform modules?

Terraform modules are reusable collections of configuration files used to standardize resources. They make infrastructure scalable, reduce duplication, improve maintainability, and enable teams to define common patterns for repeated deployments easily.

11. What is Chef?

Chef is a configuration management and automation tool that uses Ruby-based cookbooks and recipes. It ensures consistent configuration across servers using a client–server model and supports policy-based deployment for scalable infrastructure automation.

12. What is Puppet?

Puppet is a configuration management system that defines infrastructure as declarative manifests. It ensures consistent provisioning, enforces configuration policies, supports reporting, and automates system configuration for large-scale environments.

13. What is a desired state configuration?

Desired state configuration refers to defining the final expected configuration of infrastructure. IaC tools continuously check and enforce this state, ensuring systems remain aligned with defined policies and automatically correcting configuration drift.

14. What is Terraform Plan?

`terraform plan` shows the execution steps Terraform will take before applying changes. It compares the desired configuration with the current state, highlighting additions, updates, or deletions, allowing teams to verify changes before deployment.

15. What is configuration drift?

Configuration drift occurs when infrastructure changes outside the IaC pipeline, causing differences between actual and expected states. Drift leads to inconsistencies and failures. IaC tools detect and correct drift automatically to maintain stability.

16. What is Terraform backend?

A Terraform backend defines where state files are stored—local or remote (S3, GCS, Azure Storage). Remote backends enable team collaboration, state locking, encryption, and secure management of infrastructure data during deployments.

17. What is a CloudFormation Stack?

A CloudFormation Stack is a collection of AWS resources created and managed from a single template. Updating a stack updates all associated resources. Stacks support rollback, drift detection, and change sets for controlled deployments.

18. What is GitOps?

GitOps is a deployment methodology where Git acts as the single source of truth for infrastructure and application configuration. Tools continuously reconcile Git state with the cluster, enabling automated, version-controlled cloud-native infrastructure.

19. What are Ansible Playbooks?

Playbooks are YAML-based Ansible files that define tasks, roles, and configurations. They automate provisioning, orchestration, patching, and deployments. Playbooks are readable, modular, and support reusable roles for scalable automation workflows.

20. What is Terraform Apply?

`terraform apply` executes the changes proposed in the plan. It creates, updates, or deletes infrastructure resources based on configuration. After execution, the new state is written to the state file, ensuring an accurate record of deployed resources.

26. What is a Terraform Provider?

A Terraform provider is a plugin that enables Terraform to interact with external APIs such as AWS, Azure, GCP, Kubernetes, and SaaS tools. Providers expose resources and data sources, allowing Terraform to manage infrastructure using declarative configurations.

27. What is a CloudFormation Change Set?

A CloudFormation Change Set previews how updates will modify existing AWS resources before applying changes. It helps identify impacts, avoid unwanted updates, validate modifications, and safely review infrastructure changes without deployment risks.

28. What is Ansible Inventory?

Ansible Inventory is a list of managed hosts defined in INI, YAML, or dynamic scripts. It groups servers, specifies variables, and allows targeting specific environments. Dynamic inventory pulls cloud instance lists automatically from cloud provider APIs.

29. What is Policy as Code?

Policy as Code applies automated rules to enforce security, compliance, and governance using tools like OPA, Sentinel, and AWS Config. It ensures infrastructure follows organizational standards before, during, and after IaC deployments.

30. What is Terraform Workspace?

Terraform Workspaces allow multiple state files within the same configuration. They help manage different environments like dev, test, and prod while using shared code. Each workspace keeps its own state, enabling separation and safe parallel deployments.

31. What is a Pulumi Stack?

A Pulumi Stack is an isolated instance of a Pulumi program with its own configuration and state file. Stacks allow multiple environments using the same codebase, support secrets management, and enable cross-cloud deployments using real programming languages.

32. What is Terraform Import?

Terraform Import maps existing infrastructure resources into Terraform state so Terraform can manage them. This helps migrate manually created or legacy resources into Terraform-managed configurations without recreating or modifying existing resources.

33. What is Immutable Infrastructure?

Immutable infrastructure means servers are never modified after deployment—instead, new instances replace old ones. IaC tools and CI/CD pipelines help achieve repeatable, reliable deployments by enforcing stateless, versionable, and fully automated rebuilds.

34. What is a CloudFormation Nested Stack?

A nested stack is a CloudFormation stack within another stack, used to organize large templates into reusable components. This improves modularity, reusability, maintainability, and simplifies managing complex infrastructures across multiple resources.

35. What is Ansible Galaxy?

Ansible Galaxy is a public repository for sharing community-developed Ansible roles and collections. It allows teams to download reusable automation components, accelerate development, follow best practices, and standardize infrastructure automation.

36. What is Terraform Cloud?

Terraform Cloud is HashiCorp’s SaaS platform offering remote execution, state storage, version control integration, policy enforcement, collaboration, private registries, and secure variable management, enabling team-based Terraform operations.

37. How does IaC help in DevOps?

IaC enables rapid, consistent infrastructure deployment that integrates with CI/CD pipelines. It automates provisioning, reduces manual work, improves collaboration, ensures reliability, and accelerates software delivery by treating infrastructure like code.

38. What are Terraform Data Sources?

Terraform Data Sources fetch existing information from cloud providers or external systems. They allow referencing dynamic values like AMI IDs, VPCs, and secrets without creating new resources, helping build adaptive and reusable IaC configurations.

39. What is Infrastructure Drift Detection?

Drift detection identifies changes made outside IaC pipelines. Tools like Terraform, CloudFormation, and Puppet compare actual states with expected configurations, alerting teams to inconsistencies that must be corrected for stable environments.

40. What is Chef Cookbook?

A Chef cookbook is a collection of recipes, attributes, templates, and resources that define system configuration. It packages configuration logic into reusable units, ensuring consistent automation for servers, applications, and infrastructure components.

41. What is Puppet Manifest?

A Puppet manifest is a file written in Puppet DSL that defines desired configurations for systems. Manifests enforce resource states like packages, services, users, and files, providing automated configuration management across large infrastructures.

42. What is Terraform Refresh?

`terraform refresh` updates the state file with the actual infrastructure values. It helps Terraform detect external changes, synchronize configurations, and prepare accurate plans. Although less used after v0.15, it supports state consistency checks.

43. What is Ansible Vault?

Ansible Vault encrypts sensitive variables, files, or playbooks to secure secrets such as passwords and API keys. It enables safe IaC automation while protecting confidential data, supporting encryption, editing, and decryption commands.

44. What is Terraform Local-Exec and Remote-Exec?

Local-Exec executes commands on the local machine running Terraform, while Remote-Exec executes scripts on remote servers. They enable bootstrapping, configuration scripts, and integration with other tools during infrastructure provisioning workflows.

45. What is Desired State Enforcement?

Desired State Enforcement ensures infrastructure stays aligned with predefined configurations. Tools like Puppet, Chef, and Ansible continuously verify and fix deviations, maintaining system reliability and preventing unexpected configuration drift.

46. What is a Terraform Registry?

The Terraform Registry hosts official and community modules and providers for reusable infrastructure patterns. It simplifies IaC development by offering prebuilt templates for AWS, Azure, GCP, Kubernetes, and other platforms, enabling faster deployments.

47. What is Cross-Environment Promotion in IaC?

Cross-environment promotion means deploying the same IaC code across dev, test, stage, and prod using versioned modules and pipelines. It ensures consistency, reduces errors, and enables predictable, auditable infrastructure changes across environments.

48. What is the difference between Terraform and Ansible?

Terraform focuses on provisioning cloud infrastructure declaratively, while Ansible focuses on configuration management and orchestration. Terraform maintains state and creates resources; Ansible installs, configures, and manages software post-provisioning.

49. What is a CloudFormation Drift?

CloudFormation drift occurs when AWS resources change outside CloudFormation templates. Drift detection compares actual resource properties with template definitions, helping maintain consistent IaC deployments and identifying manual configuration changes.

50. What is the purpose of version control in IaC?

Version control manages changes to IaC configurations, enabling rollback, collaboration, auditing, and code reviews. It ensures infrastructure definitions evolve safely, supports GitOps workflows, and maintains a history of deployments and modifications.